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in Journal of the American Veterinary Medical Association

Summary

High fractions of inspired oxygen are commonly used during general anesthesia in birds. Observations in ducks anesthetized with halothane or pentobarbital indicated that high fractions of inspired oxygen depress ventilation. The purpose of this study was to test the hypothesis that ducks hypoventilate when breathing high fractions of inspired oxygen, compared with the same ducks breathing low fractions of inspired oxygen.

Respiratory variables were recorded in 7 ducks anesthetized with 1.4% isoflurane in oxygen. Four concentrations of oxygen (21, 40, 70, and > 90%) were used for each duck. Respiratory rate decreased as the fraction of inspired oxygen increased, but not significantly. There was a significant decrease in tidal volume as Paco2 increased. Hyperoxia was observed to contribute to hypoventilation in ducks anesthetized with isoflurane in oxygen.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine accuracy and precision of a point-of-care hemoglobinometer for measuring hemoglobin concentration and estimating PCV in horses.

Design—Prospective trial.

Animals—55 horses.

Procedure—Blood samples were obtained from 43 horses examined at a veterinary teaching hospital. Hemoglobin concentration was measured with the hemoglobinometer and by means of the standard cyanmethemoglobin method; PCV was measured by centrifugation. Blood samples were also obtained from 12 healthy horses, and PCV of aliquots of these samples was altered to approximately 5 to 80% by removing or adding plasma. Hemoglobin concentration and PCV were then measured.

Results—For samples from the clinic patients, hemoglobin concentrations obtained with the hemoglobinometer were less than concentrations obtained with the cyanmethemoglobin method; however, there was a linear relationship between concentrations obtained with the 2 methods. Breed, sex, body weight, and duration of sample storage did not significantly affect the difference between hemoglobin concentrations obtained with the 2 methods. There was a significant linear relationship between PCV and hemoglobinometer hemoglobin concentration (PCV = [2.83 X hemoglobin concentration] − 0.62). For samples from the healthy horses, a substantial negative bias was evident with the hemoglobinometer when hemoglobin concentration exceeded 16 g/dL.

Conclusions and Clinical Relevance—Results suggest that this hemoglobinometer is reasonably accurate and precise when used to measure hemoglobin concentration in blood samples from horses with a hemoglobin concentration < 16 g/dL. (J Am Vet Med Assoc 2003;223:78–83)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether dogs that received eyedrops containing phenylephrine and scopolamine would have a higher mean arterial blood pressure (MAP) when anesthetized than would dogs that did not receive the eyedrops.

Animals—37 nondiabetic and 29 diabetic dogs anesthetized for phacoemulsification and 15 nondiabetic dogs anesthetized for corneal ulcer repair (control dogs).

Procedures—Medical records were reviewed to identify study dogs. Dogs undergoing phacoemulsification received 2 types of eyedrops (10% phenylephrine hydrochloride and 0.3% scopolamine hydrobromide) 4 times during a 2-hour period prior to the procedure. Control dogs did not receive these eyedrops. Heart rate and MAP were measured before surgery in all dogs 10 and 5 minutes before, at the time of (t0), and 5 (t5) and 10 (t10) minutes after atracurium administration.

Results—MAP was greater in the 2 groups that received the eyedrops than in the control group at t0 and t5; at t10, it was greater only for the nondiabetic dogs that received eyedrops. Nine nondiabetic dogs and 1 diabetic dog anesthetized for phacoemulsification had at least 1 MAP value > 131 mm Hg; 73% of MAP values > 131 mm Hg were detected within 10 minutes after atracurium administration. At no time did a control dog have an MAP value > 131 mm Hg.

Conclusions and Clinical Relevance—Anesthetized dogs pretreated with eyedrops containing phenylephrine and scopolamine had higher MAP values than dogs that did not receive the eyedrops, suggesting the drops caused hypertension. Atracurium may interact with the eyedrops and contribute to the hypertension.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine hepatic effects of halothane and isoflurane anesthesia in young healthy goats.

Design—Randomized prospective clinical trial.

Animals—24 healthy 9-month-old female goats.

Procedure—Goats were sedated with xylazine hydrochloride and ketamine hydrochloride and anesthetized with halothane (n = 12) or isoflurane (12) while undergoing tendon surgery. End-tidal halothane and isoflurane concentrations were maintained at 0.9 and 1.2 times the minimal alveolar concentrations, respectively, and ventilation was controlled. Venous blood samples were collected approximately 15 minutes after xylazine was administered and 24 and 48 hours after anesthesia, and serum aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), alkaline phosphatase (ALP), and γ-glutamyltransferase (GGT) activities and bilirubin concentration were measured. Goats were euthanatized 25 or 62 days after anesthesia, and postmortem liver specimens were submitted for histologic examination.

Results—All goats recovered from anesthesia and survived until euthanasia. Serum SDH, GGT, and ALP activities and bilirubin concentration did not increase after anesthesia, but serum AST activity was significantly increased. However, serum hepatic enzyme activities were within reference limits at all times in all except 1 goat in which serum AST activity was high 24 and 48 hours after anesthesia. This goat had been anesthetized with halothane and had the longest duration of anesthesia. No clinically important abnormalities were seen on histologic examination of liver specimens.

Conclusions and Clinical Relevance—Results suggest that use of halothane or isoflurane for anesthesia in young healthy goats is unlikely to cause hepatic injury. (J Am Vet Med Assoc 2000;217:1697–1700)

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in Journal of the American Veterinary Medical Association

Objective

To describe dogs undergoing cesarean section in the United States and Canada, to determine perioperative management, and to calculate survival proportions.

Design

Multicenter prospective case series.

Animals

3,908 puppies from 808 dams.

Results

Survival rates immediately, 2 hours, and 7 days after delivery were 92, 87, and 80%, respectively, for puppies delivered by cesarean section (n = 3,410) and 86, 83, and 75%, respectively, for puppies born naturally (498). For 614 of 807 (76%) litters, all puppies delivered by cesarean section were born alive. Maternal mortality rate was 1 % (n = 9). Of 776 surgeries, 453 (58%) were done on an emergency basis. The most common breeds of dogs that underwent emergency surgery were Bulldog, Labrador Retriever, Boxer, Corgis, and Chihuahua. The most common breeds of dogs that underwent elective surgery were Bulldog, Labrador Retriever, Mastiff, Golden Retriever, and Yorkshire Terrier. The most common methods of inducing and maintaining anesthesia were administration of isoflurane for induction and maintenance (n = 266; 34%) and administration of propofol for induction followed by administration of isoflurane for maintenance (237; 30%).

Clinical Implications

Mortality rates of dams and puppies undergoing cesarean section in the United States and Canada are low. Knowledge of mortality rates should be useful to veterinarians when advising clients on the likelihood of puppy and dam survival associated with cesarean section. (J Am Vet Med Assoc 1998;213:365-369)

Free access
in Journal of the American Veterinary Medical Association

Summary

Platelet aggregation and adenosine triphosphate (atp) release were measured by use of the impedance method in blood samples obtained from 25 adult female Beagles before and after sedation with acepromazine (0.13 mg/kg of body weight) and atropine (0.05 mg/kg), and during general anesthesia. General anesthesia was induced by iv administration of thiamylal (average dosage, 2.1 mg/kg; range, 1.2 to 4.2 mg/kg) and was maintained with halothane in oxygen. Samples of jugular venous blood were obtained from each dog, using citrate as anticoagulant. Platelet count was done on each sample. Platelet aggregation and atp released from the aggregating platelets were measured within 2.5 hours of sample collection, using a whole-blood aggregometer. Adenosine diphosphate (adp) or collagen was used as aggregating agent. For each aggregating agent, platelet aggregation and atp release were measured over 6 minutes. After sedation with acepromazine and atropine, significant (P < 0.01) reduction was observed in platelet count (from median values of 341,000 cells/μl to 283,000 cells/μl) and in the ability of platelets to aggregate in response to adp (from 14.0 to 7.0 Ω). During the same period, maximal release of atp in response to collagen also was reduced (from 5.56 μmol to 4.57 μmol; P < 0.01); however, this difference ceased to be significant when atp release was normalized for platelet count. During general anesthesia and surgery (200 minutes after sedation), platelet count and aggregation responses to adp and collagen had returned to presedation values. None of the dogs in this study appeared to have hemostasis problems during surgery.

In conclusion, sedation with acepromazine and atropine induces measurable inhibition of adp-induced platelet aggregation that resolves during subsequent general anesthesia and surgery. Transient inhibition of platelet aggregation is not manifested by a change in gross hemostasis during surgery.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effects of hydromorphone, hydromorphone and glycopyrrolate, medetomidine, and butorphanol premedication on the difficulty and time required to pass an endoscope into the stomach and duodenum of cats anesthetized with ketamine and isoflurane.

Design—Randomized complete block crossover study.

Animals—8 purpose-bred adult female cats.

Procedures—Each cat was premedicated and anesthetized 4 times with an interval of at least 7 days between procedures. Cats were premedicated with hydromorphone, hydromorphone and glycopyrrolate, medetomidine, or butorphanol administered IM. Twenty minutes after premedication, sedation was assessed by use of a subjective ordinal scale. Cats received ketamine administered IM, and 10 minutes later a cuffed orotracheal tube was placed and anesthesia maintained with isoflurane. Cats breathed spontaneously throughout the procedure. When end-tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was begun. The times required to pass the endoscope through the cardiac and pyloric sphincters were recorded, and the difficulty of endoscope passage was scored by use of a subjective ordinal scale.

Results—No significant differences in difficulty or time required to pass the endoscope through the cardiac and pyloric sphincters were found among premedicant groups. Premedication with medetomidine resulted in the greatest degree of sedation and longest time to return to sternal recumbency.

Conclusions and Clinical Relevance—Results suggest that hydromorphone, hydromorphone and glycopyrrolate, medetomidine, and butorphanol at the doses tested can be used satisfactorily to premedicate cats prior to general anesthesia for gastroduodenoscopy. (J Am Vet Med Assoc 2004;225:540–544)

Full access
in Journal of the American Veterinary Medical Association